Method of producing expanded metal lath



July 21, 1942 B. T. BALLAo-Er AL METHOD OF PRODUCING EXPANDED METAL LATH Fi'l-ed Nov. 1.. 30. 1939 O O 2 O2 OX 22 O O Q 0o Patented July 21, 1942 METHOD OF PRODUCING EXPANDED METAL LATH Bernard T. Ballard a Warren, Ohio, assignors to ad David M. Fleming,

United States Gypsum Company, Chicago, 11]., a corporation of Illinois Application November 30, 1939, Serial No. 306,860

8 Claims.

This invention relates to the method of making an improved expanded metal lath, and particularly flattened -metal lath.

In making metal lath such as is commonly used as a plaster base, it has lacked uniformity, not only in different sheets, but between different portions of the same sheet.

This flattening step, which fused with right angles to the plane of the sheet could not be satisfactorily flattened. When sheets of this nature are passed through pressure rolls or other flattening means, many of the bonds perpendicular to the plane of the sheet are just mashed or crushed and are broken away from their adjoining strands.' Even in the unfractured portions of the sheet, the shape and size of the openings vary considerably.

However, a sheet of expanded metal produced by the method hereinbefore described of slitting, flattening and expanding, and having the bonds all lying in substantially parallel planes at an acute angle to the plane of the sheet, may be passed between pressure rolls or other flattening means and satisfactorily flattened.

It is therefore an object of this invention to provide a method for producing expanded metal lath with openings of relatively great uniformity.

Another object is to provide a method for producing diamond mesh metal lath having all the bonds in substantially parallel planes at an acute angle to the plane of the sheet.

A further object of this invention is to provide a method for producing a sheet of flat expanded metal of substantially uniform strength and resistance to breaking throughout, and hav ing openings of comparatively great uniformity.

Further objects and advantages will be apparent from the following description when considered with the accompanying drawing, in which- Fig. 1 is a diagrammatic representation illustrating mechanism which may be used in carrying out the present method.

Fig. 2 is a plan view of a slitted blank having overlapping slits formed therein.

Fig. 3 is a cross sectional view taken along the line 33 of Fig. 2 and illustrates the offsetting of the strands and bonds in the slitted blank.

Fig. 4 is a cross sectional view through a transverse row of bonds showing the same after the blank has been slitted and then flattened.

Fig. 5 is similar to-Fig. 4, but is a cross sec-' tional view through a transverse row of strands.

Fig. 6 shows a sheet of prior art expanded the sheet.

Fig. 7 shows a sheet of lath which may be used as a plaster base which has been formed by slitting, flattening and expanding, and in which all of the bonds are in substantially parallel planes at an acute angl to the plane of the sheet.

v Fig. 8 is a view of flat metal lath formed from metal lath of the type illustrated in Fig. 7.

Referring more particularly to the drawing, there is shown a thin metal blank I which is passed between a pair of cutters such as rotary cutters 2. The slitting produces a blank 3 having transverse rows of bonds 4 and I and-transverse rows of strands 8. The blank I is thereafter passed between pressure rolls 1, or other flattening means which force all the strands and bonds of the slitted sheet back into substantially a common plane, as shown in Figs. 4 and 5.

It has been found that the flattening step between the slitting and expanding tends to eliminate irregularity in the finished sheets as there is a uniform resistance to expansion.

The thus flattened and slitted blank is then fed to expanding mechanism such as a diverging chain expander diagrammatically illustrated at 8. This produces expanded metal lath such as shown in Fig. 7 in which all the bonds lie at an acute angle to the plane of the sheet insubstantially parallel planes, and in which the openings are relatively uniform throughout. Expanded sheets of this character may then be fed through pressure rolls means, without fracturing of the sheet, resulting in a uniform, flat product, as illustrated in Fig. 8.

Ihe method heretofore described in connection with the manufacture of diamond mesh metal lath is also applicable to the manufacture of other types, including herring-bone mesh, such for example as shown in Manofsky Patent No. 1,618,666, dated Februrary 22, 1927.

In producing the series of parallel slits are formed diagonally of the blank with alternate series being oppositely disposed. Reciprocating cutters are generally employed for this. when these blanks are expanded in the usual manner, such as by a diverging chain expander or by rolls and diverging guides, there is a tendency for some of the series of strands to twist. By flattening the blank before expanding to bring the offset strands back into a common plane, the resistance to expan sion is substantially uniform and twisting of the strands is avoided. Therefore the expanded sheet is relatively uniform throughout.

It is to be understood that in carrying out the present method, various modifications and changes within the skill of the art may be made, and therefore we wish to be limited only by the scope of the prior art and the appended claims.

We claim:

1. The method of forming expanded metal lath of relatively great uniformity which comprises slitting a thin metal blank to form strands with adjacent strands offset from each other, flattening the slitted portions of said blank substantialy without reducing the gauge thereof to bring the offset strand portions into a substantially common plane and provide a practically uniform resistance to expansion, and pulling the edges of said blank in substantially opposite directions while permitting said strands to arrange themselves at an angle to the plane of the expanded sheet during expansion thereof.

2. The method of forming expanded metal lath of relatively great uniformity which comprises slitting a thin metal blank to form strands with adjacent strands offset from each other, flattening the slitted portions of said blank substantially without reducing the gauge thereof to bring the offset strand portions into a substantially herring-bone type of mesh,

9, or other flattening common plane and provide practically uniform resistance to expansion, and continuously feeding said blank and simultaneously forcing the edges thereof in substantially opposite directions while permitting said strands to arrange themselves at an angle to the plane of the expanded sheet during expansion thereof.

3. The method of forming expanded metal lath of relatively great slitting a thin metal blank to form strands with adjacent strands offset from each other, flattening the slitted portions of said blank substantially without reducing the gauge thereof to bring the offset strand portions into a substantially common plane and provide a practically uniform resistance to expansion, and expanding the slitted and flattened portions of said blank by positively guiding .the edges thereof in diverging directions while continuously advancing said blank, said strands being free to arrange themselves at an angle to the plane of said expanded sheet during expansion thereof.

4. The method of forming expanded metal lath of relatively great uniformity which comprises slitting a thin metal blank by forcing adjacent portions thereof in opposite directions substantially perpendicular to the plane of the blank to form strands offset from each other, rolling the slitted portions of said blank substantially without reducingthe gauge thereof to bring the oflset strand portions into a substantially common plane and provide a practically uniform resistance to expansion, and thereafter expanding the slitted and flattened portions of said blank by positively guiding the edges thereof in diverging directions while continuously advanc ing said blank, said strands being free to arrange themselves at an angle to the plane of said expanded sheet during expansion thereof.

5. The method of forming herringbone metal lath which comprises slitting a thin metal blank to form alternate series of oppositely dispoud offset strands, flattening the slitted portions of said blank substantially without reducing the gauge thereof to bring said offset strand portions into a substantially common plane and provide a practically uniform resistance to expansion, and thereafter expanding the slitted and flattened portions of said blank by positively guiding the edges thereof in diverging directions while continuously advancing said blank, said strands being free to arrange themselves at an angle to the plane of said expanded sheet during expansion thereof.

6. The method of forming diamond mesh expanded metal lath which comprises slitting a thin metal blank to form strands and bonds with adjacent strands offset from each other, flattening the slitted portions of said blank substantially without reducing the gauge thereof to bring all said bonds and strands into a substantially common plane and provide a practically uniform resistance to expansion, and thereafter positively guiding the edges of said blank in diverging directions while continuously advancing the same to form an expanded sheet, said bonds being free to arrange themselves in substantially parallel planes at an angle to the plane of said expanded sheet during ,the expansion thereof,

'7. The method of forming flat expanded metal lath which comprises slitting a thin metal blank to form strands with adjacent strands offset from each other, flattening the slitted portions of said blank substantially without reducing the gauge thereof to bring the offset strand portions into a substantially common plane and provide uniformity which comprises 

